The bike is the longest leg, the biggest engine, and the one most age-group athletes under-build and over-spend. It's where aerobic fitness is made — and where the run is won or lost before you ever lace up.
The bike is the longest single effort in any triathlon, and the way you ride it dictates everything that follows. Yet two patterns repeat in almost every age-group athlete: they're undertrained on the bike relative to its importance, and they overspend on it in the first half of a race. Both are fixable, and fixing them is the fastest way to a better overall result.
It's also the smartest place to build fitness. The bike is low-impact and high-volume-tolerant: you can accumulate large aerobic load on the bike that your legs and joints would never survive from running. That makes it the engine room of the whole system — the place we build the chronic fitness that everything else draws on.
In a recovery-led system, the bike is the moderate-cost middle ground. On a green-light day it carries your biggest sessions. On an amber day it's where we keep the aerobic work going at an honest, controlled power while the run stays on the shelf.
“The bike doesn't win the race. But riding it wrong loses the run — every time.”
Everything on the bike is anchored to one number: Functional Threshold Power — the highest power you can hold for about an hour. Test it with a 20-minute effort (FTP = 20-min average × 0.95), retest every 6–8 weeks, and train to zones built from it.
| Zone | % FTP | What it builds |
|---|---|---|
| Z1 — Recovery | <55% | Active recovery, spinning out |
| Z2 — Endurance | 55–75% | The aerobic base — the foundation |
| Z3 — Tempo | 76–88% | Sustained aerobic strength |
| Sweet Spot | 88–93% | Best return: threshold power, lower cost |
| Z4 — Threshold | 94–105% | Raises FTP directly |
| Z5 — VO₂max | 106–120% | Top-end aerobic ceiling |
Two truths shape the work. First, sweet spot (88–93%) is the highest-value place to spend interval time — most of the benefit of threshold work at a fraction of the recovery cost; a session of 2 × 20 minutes there does more for a triathlete than chasing all-out FTP efforts. Second, the aerobic base at 60–70% FTP is non-negotiable. You cannot out-interval a weak engine. Most athletes have this backwards — too much intensity, not enough easy volume.
Riding at 85–95 rpm isn't a style preference — it's a strategy for the run. A higher cadence shifts load away from the muscles (peripheral fatigue) and toward the cardiovascular system (central fatigue). On a long bike, central fatigue is far easier to sustain, and crucially it leaves your leg muscles less wrecked for the run. Mashing a big gear below 80 rpm at threshold loads the quads and the knees, and you pay for it the moment you start running.
If your natural cadence sits low, build it deliberately: weekly high-cadence sets at 100–110 rpm in Zone 2 for a few weeks, raising your everyday cadence a few rpm per training block.
Fitness gets you to the start line. Pacing gets you to the finish. The bike-to-run handover is the hinge of the whole race, and it's a discipline you rehearse.
The single most expensive mistake in long-course racing happens in the first 30 km, when adrenaline and fresh legs make 80% of FTP feel like 70%. Those stolen watts don't just cost you that half-hour — the excess glycogen depletion and fatigue compound across the remaining hours and detonate on the run. Ride to power, keep it even, and treat holding back early as the hardest, most important skill you own.
The bike is the engine room of the protocol. Because it's low-impact, it's where the R.A.C.E. Framework builds chronic aerobic fitness without the structural cost of running — and where your biggest sessions land on high-readiness days. Its power data feeds your training-load model directly, so the system knows exactly how much the engine took out of you and how long it'll take to come back.
Pace it well and the run holds together. Build it patiently and the whole system rises with it. Read your readiness first and you'll know which bike session today actually deserves.
Swim, bike, run, strength, recovery, and the mind are coached as one system, organised around your nervous system. Here's where to go next.
Train the right zones, pace with discipline, and ride the bike that sets up the run — inside a system built around how you recover.